diff options
author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2008-01-25 21:08:24 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-01-25 21:08:24 +0100 |
commit | e260be673a15b6125068270e0216a3bfbfc12f87 (patch) | |
tree | f50760606d395bf6faa9e865f814761a3c88d32c /include/linux/rcupreempt.h | |
parent | e0ecfa7917cafe72f4a75f87e8bb5d8d51dc534f (diff) |
Preempt-RCU: implementation
This patch implements a new version of RCU which allows its read-side
critical sections to be preempted. It uses a set of counter pairs
to keep track of the read-side critical sections and flips them
when all tasks exit read-side critical section. The details
of this implementation can be found in this paper -
http://www.rdrop.com/users/paulmck/RCU/OLSrtRCU.2006.08.11a.pdf
and the article-
http://lwn.net/Articles/253651/
This patch was developed as a part of the -rt kernel development and
meant to provide better latencies when read-side critical sections of
RCU don't disable preemption. As a consequence of keeping track of RCU
readers, the readers have a slight overhead (optimizations in the paper).
This implementation co-exists with the "classic" RCU implementations
and can be switched to at compiler.
Also includes RCU tracing summarized in debugfs.
[ akpm@linux-foundation.org: build fixes on non-preempt architectures ]
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Reviewed-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/rcupreempt.h')
-rw-r--r-- | include/linux/rcupreempt.h | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h new file mode 100644 index 00000000000..ece8eb3e415 --- /dev/null +++ b/include/linux/rcupreempt.h @@ -0,0 +1,86 @@ +/* + * Read-Copy Update mechanism for mutual exclusion (RT implementation) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2006 + * + * Author: Paul McKenney <paulmck@us.ibm.com> + * + * Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com> + * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. + * Papers: + * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf + * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) + * + * For detailed explanation of Read-Copy Update mechanism see - + * Documentation/RCU + * + */ + +#ifndef __LINUX_RCUPREEMPT_H +#define __LINUX_RCUPREEMPT_H + +#ifdef __KERNEL__ + +#include <linux/cache.h> +#include <linux/spinlock.h> +#include <linux/threads.h> +#include <linux/percpu.h> +#include <linux/cpumask.h> +#include <linux/seqlock.h> + +#define rcu_qsctr_inc(cpu) +#define rcu_bh_qsctr_inc(cpu) +#define call_rcu_bh(head, rcu) call_rcu(head, rcu) + +extern void __rcu_read_lock(void); +extern void __rcu_read_unlock(void); +extern int rcu_pending(int cpu); +extern int rcu_needs_cpu(int cpu); + +#define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); } +#define __rcu_read_unlock_bh() { local_bh_enable(); rcu_read_unlock(); } + +extern void __synchronize_sched(void); + +extern void __rcu_init(void); +extern void rcu_check_callbacks(int cpu, int user); +extern void rcu_restart_cpu(int cpu); +extern long rcu_batches_completed(void); + +/* + * Return the number of RCU batches processed thus far. Useful for debug + * and statistic. The _bh variant is identifcal to straight RCU + */ +static inline long rcu_batches_completed_bh(void) +{ + return rcu_batches_completed(); +} + +#ifdef CONFIG_RCU_TRACE +struct rcupreempt_trace; +extern long *rcupreempt_flipctr(int cpu); +extern long rcupreempt_data_completed(void); +extern int rcupreempt_flip_flag(int cpu); +extern int rcupreempt_mb_flag(int cpu); +extern char *rcupreempt_try_flip_state_name(void); +extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu); +#endif + +struct softirq_action; + +#endif /* __KERNEL__ */ +#endif /* __LINUX_RCUPREEMPT_H */ |